Automated beverage dispensers have become a commonality in recent years. Food courts, cafeterias, office buildings and community centres name only a few locations where users want freshly brewed drinks but have neither the staffing resources nor the tools and ingredients required to make them. As such, self-contained, automated brewing devices such as those disclosed in U.S. Pat. No. 5,927,553 to Ford and U.S. Pat. No. 6,182,555 to Scheer, et al. are placed in these locations to provide the service that would otherwise be unavailable.
Many of these machines contain dispensers for beverage additives such as sugar or flavouring, allowing users to adapt the dispensed drinks to their individual tastes. Brewing machines often have a plurality of additive dispensers, each of which discharges a pre-determined quantity of additive to be mixed into the beverage before the drink is cupped and released to the customer. It is known from the prior art that the mechanics behind the dispensing of beverage additives often involve a rotating auger member driven by a motor, whereby the auger's action causes a volume of powder to be moved laterally to a discharge port.
However, the hopper-and-auger combinations taught by the prior art lead to some difficulties. The first difficulty results from the fact that the hoppers have flat bases. FIG. 1 shows the dispensing port region of a typical auger dispenser taught by the prior art. This often leads the powder to be dispensed at a variable rate. Powder 10, especially that of very fine granules, is prone to settling when left undisturbed for a period of time and consequently forms clumps 14. When one such clump forms in between two blades of an auger 11, it tends to move as a unit once the auger is set in motion. If only part of a clump 13 reaches the dispensing port 12 once the auger stops, it may be partially suspended over the port as there is no substantial force in place to break the clump apart. This can lead to a discrepancy in the expected quantity of powder released, since the clump will either remain suspended by virtue of its integrity causing an insufficient release of additive, or will fall through the port entirely causing an excessive release of additive. This can also cause significant “dribbling” of powder, since any suspended clump may break apart and fall through the port if the machine is jostled while not in use.
An issue contributing to this problem is the orientation of the flight of the auger after the dispense is completed. Those skilled in the art will understand that such augers can be of a conveyor type of auger, such as the one shown in FIG. 8. Most such augers have a helical shaped flight along a length of a shaft with a predetermined pitch. One full revolution of the auger can be calibrated to dispense the powder in a single pitch of the flight. When a full pitch is dispensed, the bottom edge of the flight is substantially positioned adjacent to the opening edge of the port, hence there is little to no non-dispensed powder remaining. However fractions of a revolution, such as a 0.5 revolution will cause dispensing inaccuracy. This is because the non-dispensed powder is positioned between a rear flight edge and the port. Therefore this powder is prone to cascading in an “avalanche” effect if the machine is jostled, which is likely in most service industry environments where such a dispensing machine would be used. This is referred to as a “high-low” effect, because the first dispense operation will provide more than the desired amount of powder, while the next dispense operation will provide less than the desired amount of powder since some of it has been inadvertently dispensed in the first dispense operation.
Furthermore, the augers taught by the prior art often leave a noticeable space between the tips of the blades themselves and the bottom of the hopper. This leads to wasted powder 15, as quantities of the substance may settle to the bottom of the space and remain unused, as it is unreachable by the auger blades. This is both wasteful and unhygienic, as microorganisms can culture in the stagnant substance over time.
An additional difficulty with the hoppers of the prior art is that they are difficult to clean. Because of the nature of the powders dispensed, it is essential that all moisture be removed from the hopper once the cleaning process is complete. A flat-bottomed hopper, however, will not drain fluid unless it is tilted to an awkward angle or allowed to stand upside-down throughout the drying process.
It is, therefore, desirable to provide a dispenser system for fine powders which is easy to clean, efficiently uses all of the powder contained in the hopper and releases powder at a constant rate.